This invention relates to an improved one-way clutch assembly and applications for such a clutch.
It is well known to employ one-way clutches for a wide variety of uses. Such clutches are operative to provide a driving relationship between a first member and a second member and yet permit the second member to overrun the first member under certain conditions. For example, such a one-way clutch may be utilized in conjunction with the starting mechanism of an internal combustion engine. The one-way clutch provides a driving connection between the starter motor and the engine output shaft for rotating the engine output shaft when the starter motor is operated to provide starting. However, once the engine starts and the starter motor is stopped, the one-way clutch permits the engine output shaft to be driven without driving the starting motor.
It should be seen, therefore, that relatively large power must be transmitted through the one-way clutch. Normally the one-way clutch includes an outer member in which recesses are formed that receive wedging members and which have wedging surfaces against which the wedging members react. An inner member is rotatable relative to the outer member and has its outer surface engaged by the wedging members so as to provide a driving relationship between them. However, the wedging members are permitted to move away from the wedging surface of the outer member to permit overrunning. It should be readily apparent that the outer member must be formed from a very strong material to resist the large tensile forces exerted upon its wedging surfaces. Because of this, one-way clutches of the type heretofore utilized have been quite heavy.
Recently, it has been proposed to form the outer member from a two-piece construction with one of these pieces being formed from a lighter weight, less strong material and which defines only the recesses in which the wedging members are received. A second, considerably stronger element, is fixed relative to the first member and has projections that extend into the recesses and which form the actual wedging surfaces. In this way, the weight can be reduced significantly without sacrificing the strength of the unit.
It is a first object of this invention to provide an improved one-way clutch of the aforenoted type wherein a further weight reduction is possible.
It is another object of this invention to provide an improved arrangement for reinforcing the member forming the wedging surfaces through its attachment to another related element so as to further reduce the overall weight of the one-way clutch.
It should be apparent from the foregoing description of the construction of a one-way clutch that it is a relatively complicated structure. The outer member must form recesses for receiving the wedging elements and also is required to form a reaction surface against which biasing means operate for biasing the wedging members into engagement with the related inner and outer member surfaces. As such, if the two elements of the outer member are formed as single pieces, the cost of manufacturing them can be quite significant.
It is, therefore, a further object of this invention to provide an improved and simplified construction for a one-way clutch.
It is another object of the invention to provide a one-way clutch arrangement that may be conveniently and inexpensively manufactured.
It should be apparent that the amount of power that may be transmitted through a one-way clutch is dependent upon the surface area of contact between the wedging members and the corresponding surfaces which they engage. In a given physical location, however, there is a practical limit to the amount of surface area which is possible.
It is, therefore, a further object of this invention to provide an improved one-way clutch that is compact and which is capable of transmitting larger amounts of power than prior art type of devices.
In one-way clutches of the type having a composite outer member, i.e., one made up of a plurality of pieces from different materials, it has been the practice to provide the wedging surfaces by means of individual projections formed from the wedging element of the outer member. As a result, the individual wedging surfaces are subjected to bending loads and this further reduces the amount of power which can be transmitted.
It is, therefore, a still further object of this invention to provide an improved high strength, composite one-way clutch.